JP2005301044A - Belt fixing control device for belt fixing device - Google Patents

Abstract

A belt shift control device for a belt fixing device capable of preventing a shift of a fixing belt with a simple and inexpensive configuration without providing a complicated mechanism including a new driving means such as a swing mechanism and a solenoid. To provide.
A drive roller that drives an endless belt, one or more driven rollers that stretch the endless belt, and at least one of the drive roller or the driven rollers includes a heating body, and the endless belt In a belt fixing device that suspends and supports the heating body, the heating body is disposed at least near both ends of the endless belt in the longitudinal direction of the roller, and the relative heating amount of the heating body on one end side and the heating body on the other end side is changed. Possible heating control means and detection means for detecting the deviation in the width direction of the endless belt, and based on the detection result of the detection means, the heating amount on one end side and the other end side is determined based on the belt deviation direction end portion> Control is performed so as to be the other end.
[Selection] Figure 1

Description

  The present invention relates to a belt shift control device for a belt fixing device provided in an image forming apparatus such as a copying machine, a laser beam printer, and a facsimile machine.

  For example, as a practical device of an image fixing device in an image forming apparatus such as an electrophotographic copying machine, a belt (film) fixing type device using a thin film belt (fixing film) that is driven to move is known. (Patent Document 1 etc.).

  This is a heat-resistant, thin-film endless belt that is suspended and supported between at least two members and rotationally driven, and a transfer material to be image-fixed is brought into close contact with the outer surface of the rotating belt and conveyed together with the belt. In this close-conveying process, the heat of the heating element placed inside the belt is applied to the transfer material via the belt to heat and fix the image. Quick start characteristics with little rise time to the specified fixing temperature And has the advantage of being able to save power.

  Thus, in an apparatus for moving and driving a belt, such as the apparatus of the above example, the belt moves in the direction perpendicular to the moving direction of the belt along the length of the member supporting the belt (hereinafter referred to as the belt moving process). The belt width direction) is shifted toward the one end side or the other end side of the belt width direction more or less naturally, and is easily displaced from the reference position in the belt width direction.

  The cause of misalignment due to the shifting of the belt includes parallelism and twisting between the members that suspend and support the belt, but there is a limit to increasing the accuracy of these, only improving the accuracy. Therefore, it is difficult to prevent the belt from moving as described above.

  In the image fixing apparatus of the belt fixing system of the above example, the belt is a thin film having a thickness of less than about 40 μm, and the material is a heat-resistant material such as polyimide with little elasticity. In other words, it is difficult to suppress the belt conveying roller as the belt suspending and supporting member by simply changing the shape of the belt conveying roller to a drum-shaped crown shape or the like.

  Therefore, it is known that such an apparatus is provided with a belt deviation control mechanism as means for stably conveying the belt. As such a belt deviation control mechanism, means for detecting the deviation position of the belt in the width direction is provided, and based on information such as the position and the deviation direction of the belt suspending support member such as a belt conveying roller. Among them, there is a mechanism that displaces the inclination of at least one shaft with a solenoid or the like, or a stepless displacement with a motor or the like to control the belt displacement direction to correct the belt displacement. It was.

JP-A-63-313182

  However, in the mechanism for displacing the inclination of the shaft of the belt suspension support member, a support structure for swinging the shaft is required. As a result, not only the apparatus becomes complicated, but also the assembly work and parts replacement, etc. There were problems such as making maintenance work complicated. Further, driving means such as a solenoid and a motor have to be arranged only for correcting the deviation of the belt, and problems remain in terms of cost and arrangement space.

  Accordingly, an object of the present invention is to provide a belt fixing device that can prevent the fixing belt from being displaced with a simple and inexpensive configuration without providing a complicated mechanism including a new driving means such as a swing mechanism and a solenoid. The object is to provide a belt shift control device.

  In order to achieve the above object, the present invention provides a driving roller for driving an endless belt, one or more driven rollers for stretching the endless belt, and at least one of the driving roller or the driven rollers as a heating element. A belt fixing device that suspends and supports the endless belt by heating, the heating body is disposed at least near both ends of the endless belt in the longitudinal direction of the roller, and the heating body at one end and the heating at the other end A heating control means capable of changing the relative heating amount of the body and a detection means for detecting a deviation in the width direction of the endless belt are provided, and the heating amounts on one end side and the other end side based on the detection result of the detection means, Control is performed so that the belt end side direction end portion> the other end portion.

  According to the present invention, a new driving means such as a solenoid or a motor or a roller shaft swing is corrected in order to correct the deviation of the fixing belt by dividing and controlling the heating body inside the belt stretching roller necessary for the original belt fixing mechanism. The moving mechanism can be eliminated.

  In addition, a simple control circuit is added to the fixing device in which the heating body is divided in advance in the belt width direction for the purpose of preventing excessive temperature rise of the non-sheet passing portion when the small size transfer material is continuously fed. Only the belt offset can be corrected, and no mechanical cost is incurred.

  As described above, the present invention can provide a belt deviation control device that can reliably correct the deviation of the fixing belt while saving space and cost.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 4 is a schematic longitudinal sectional view of a belt fixing device showing an embodiment of the present invention.

  In FIG. 4, 1 is a fixing belt, 2 is a driving roller, 3 is a driven roller, 4 is a tension roller, 5 is a pressure roller, and 6 is a sensor. The fixing belt 1 has a heat-resistant and thin-film endless shape, and is suspended and supported between the driving roller 2, the driven roller 3, and the tension roller 4. The pressure roller 5 is pivotally supported on the outer surface of the fixing belt 1 so as to be rotatable with a predetermined pressure.

  When driving is transmitted to the driving roller 2 from a driving source (not shown), the driving roller 2 rotates in the direction of the arrow in the figure, and the fixing belt 1 is rotated by the frictional resistance of the fixing belt 1 and each roller. A transfer material to be image-fixed is brought into intimate contact with the outer surface of the fixing belt 1 and conveyed together with the fixing belt 1, and the heat of the heating body disposed inside the driven roller 3 is transferred via the fixing belt 1 in the adhesion and conveyance process. To heat and fix the image.

  Here, the belt deviation control device, which is a feature of the present invention, will be described in detail.

  FIG. 3 is a cross-sectional view of the principal part of the driven roller 3 in FIG. 4 cut in the longitudinal direction. In FIG. 3, 11 is a flange, 12 is a bearing, 13 is a roller base material, and 14 is a heating element.

The roller base 13 is integrally formed with the flange 11 with a material having a relatively high thermal conductivity and linear expansion coefficient, and is rotatably supported by bearings 12 at both ends. The heating element 14 arranged inside the roller base 13 is composed of three independent halogen heaters 14a (main heater), 14b (sub heater F), 14c (sub heater R), and is mechanically fixed to the apparatus side plate. ing. The heater 14 a (main heater) has a heat generating portion in a region inside the both ends in the width direction centering on the center in the width direction of the fixing belt 1, and the heater 14 b (sub-heater F) is one end in the width direction of the fixing belt 1. The heater 14 c (sub-heater R) has a heat generating portion in a region near the other end in the width direction of the fixing belt 1. Then, all the heaters 14 a, 14 b, 14 c are energized to generate heat, and the temperature of the fixing belt 1 is raised to nearly 200 ° C. via the roller base material 13. At this time, the roller base 13 is thermally expanded at the heat generating portion of each heater. For example, if the outer diameter of the driven roller 3 is φ20 mm and the material of the roller base 13 is zinc die casting, the outer diameter of the driven roller 3 is about φ21.3 mm (Zn linear expansion coefficient is 33 × 10 ^{– 5} / ° C.).

  On the other hand, when the fixing belt 1 is rotated and moved to continue the fixing operation, the fixing belt 1 is shifted in the width direction due to various factors. A sensor 6 shown in FIG. 4 is a photo interrupter, and detects a state in which the fixing belt 1 approaches a predetermined amount in the width direction.

  In the above configuration, FIG. 1 shows a belt shift control state when a shift of the fixing belt 1 is detected. In FIG. 1, when a shift in the left direction in the figure is detected while all the heaters 14 are heated. The energization of the heater 14c (sub heater R) in the right direction in the figure is stopped by a control unit (not shown). At this time, if the roller temperature near 200 ° C. is reduced by about 20 ° C. in the vicinity of the heater 14c in other regions, the outer diameter of the driven roller 3 has a gradient of 120 to 130 μm.

  FIG. 5 shows the relationship between the forces received by the fixing belt 1 in a state where the gradient of the outer diameter of the driven roller 3 is generated.

  The fixing belt 1 receives a uniform force F in the normal direction of the roller surface in the belt width region, but in the same figure, due to the gradient of the surface of the driven roller 3 formed by the difference in thermal expansion between the heating part and the non-heating part, A force that moves the belt in the width direction acts in the middle-up direction.

  On the other hand, if the friction coefficients of the fixing belt 1 and the driven roller 3 are different in the belt width direction, a force that opposes the action direction may be applied. However, when the roller diameter is varied by heat as in the present invention, the friction is reduced. There is no significant change in the coefficient, and the belt offset force is governed by the acting force in the normal direction of the roller surface.

  In this embodiment, a halogen heater is used as the heating element. However, a ceramic heater or an electromagnetic induction heating element may be divided in the belt width direction.

  Further, in the present embodiment, the end heater in the direction in which it is desired to correct the deviation of the belt during the fixing operation is stopped, but the energization amount is decreased, or as shown in FIGS. When the fixing operation is not performed, the roller may be heated and expanded only at the end portion in the belt shift direction to control the shift.

  Furthermore, in this embodiment, the heating element is disposed on the driven roller, but it may be disposed on any of the rollers that suspend and support the fixing belt, such as a driving roller and a tension roller.

  It is generally known that the effect of moving the belt in the width direction is increased when the diameter of the tension roller is varied or when the diameters of a plurality of rollers are varied simultaneously.

  The embodiment is not limited to this, that is, detecting the shift state of the fixing belt, and receiving the detection result, the light distribution of the belt suspension tension support roller is made smaller than the end portion in the shift direction. As long as the configuration is the same, the same effect can be obtained.

  The present invention can be applied to a belt shift control device of a belt fixing device provided in an image forming apparatus such as a copying machine, a laser beam printer, or a facsimile.

FIG. 5 is a cross-sectional view illustrating a belt shift control state in the belt fixing device according to the embodiment of the present invention. It is sectional drawing which shows the shift | offset | difference control state of the 2nd belt in the belt fixing apparatus of embodiment of this invention. It is principal part sectional drawing which shows the belt shift control structure in the belt fixing apparatus of embodiment of this invention. 1 is a schematic longitudinal sectional view of a belt fixing device according to an embodiment of the present invention. It is explanatory drawing of the belt deviation control action of embodiment of this invention. It is explanatory drawing of the 2nd belt deviation control action of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixing belt 2 Drive roller 3 Driven roller 4 Tension roller 5 Pressure roller 6 Sensor 11 Flange 12 Bearing 13 Roller base material 14 Heating body (heater)

Claims (1)

A driving roller for driving the endless belt, one or more driven rollers for stretching the endless belt, and at least one of the driving roller or the driven rollers has a heating body, and the endless belt is heated and suspended. In the belt fixing device that supports the tension,
A heating body is disposed at least near both ends of the endless belt in the longitudinal direction of the roller, and a heating control means capable of changing the relative heating amount of the heating body on one end side and the heating body on the other end side, and the width direction of the endless belt A detecting means for detecting the deviation, and based on the detection result of the detecting means, the heating amount on one end side and the other end side is controlled so that the edge direction in the belt deviation direction> the other end. A belt shift control device for the belt fixing device.

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